PROTEIN Dept. of Medical Nutrition Medicine School Padjadjaran University.

PROTEIN

Dept. of Medical Nutrition

Medicine School Padjadjaran University

PROTEIN

A compound of C,H,O and N molecules that bind in a fashion way to form amino acids

Amino acids bind to each other to form protein

Amino acids bound --> peptide boundProtein Nitrogen (PN)Non Protein Nitrogen (NPN)

Classification of amino acid

1. Essential amino acid (EAA) Could not synthesized by the body Should get from outside the body (Exogen) Adults need 8 essential amino acids which

are : isoleusin, leusin, lysin, phenilalanin, methionin, threonin, tryptophan, valin

Children need histidin & arginin adjacent to the 8 essential amino acids mentioned above

Essential amino acids

1. Isoleucine 8. Valin

2. Leucine 9. Histidin

3. Lysin 10.Arginin

4. Methionine

5. Phenylalanine

6. Threonine

7. Tryptophan

2. Non essential amino acids (Non EAA)

Synthesized by the body from nitrogen and amino acid carbon chain

Non essential amino acids are important to the body but not essential from food (exogen)

Non essential amino acids1. Glycine 11. Glutamine2. Glutamic acid 12. Hydroxy glut acid

13. Hydroxy lysine3. Arginine 14. Hydroxy proline4. Aspartic acid 15. Thyroxine5. Proline 16. Norleucine6. Alanine 17. Cystine7. Serine 18. Taurine8. Tyrosine 19. Carnitine9. Cystein10. Asparagine

Protein classified as follow :1. Complete Protein

- High biologic value (HBV)- Contain all EAA- Sufficient quantum of EAA - Meet the body needs- Able to support growth and to maintain body tissue

E.g. : egg, meat, poultry, fish & milk

2. Half complete protein :- Contain all of EAA

- Insufficient quantum of EAA

- Able to maintain adult health

- Unable to support children growth

E.g. : rice, wheat, tapioca

3. Incomplete Protein :- Contain fewer EAA

- Lesser EAA quantum

- Inadequate to maintain health

- Unable to support growth

E.g. : gelatin, zein on corn

Role of Protein

Provide amino acids for :Growth and developmentMaintain the body tissuesProduce energyProtein synthesis

Protein food sources

Protein in the food should provide adequate quality and quantity that meet the body need.

Animal Protein

High biological value Complete proteinEquivalent to body protein composition Digestible and well absorb by the

intestine

Plant ProteinWithin the plants, protein covered by

cellulose wall Plant proteins have lower bioavailability

1. Animal protein food sources

Milk (contain 1-4% of protein)Egg (± 12%)Fish (10-20%)Meat(18-20%)Chicken

2. Plant protein food sources Grain products ; rice, wheat (flour)Nuts ; (15-25%)

green bean (± 22,2%)soybean (35%)peanut (25,3%)bean kacang bogor (10%)kacang mete (21,2%)

3. Plant protein food sources :

Tempe (10-18%)Oncom (13%)Tauco (10,4%)Tofu (7-8%)Emping Melinjo (12%)Santan murni (4,2%)

The proteins synthesized in the body if there were complete and adequate amount of amino acids.

The quality of protein rely on : availability of all EAA ; adequate amount (quantum) that meet the body need.

Protein quality assessment Assessment of protein quality base

on EAA composition.

Protein with complete EAA in adequate amount is called Protein Reference or Provisional Amino Acid Pattern (PAAP)

Amino acids pattern (FAO/WHO, 1973)EAA mg.AA/gr.nitrogen Isoleusin 250 Leusin 440 Lisin 340 Fenilalanin 200 Tyrosin 180 AA contain S 220 Metionin 220 Threonin 250 Triptofan 60 Valin 310Source : Wohl & Godhart, 2nd Edition

EAA in the food which have lower concentration (the lowest concentration) than PAAP ---> Limiting Amino Acid (LAA)

Percentage (%) of LAA ---> Chemical Score.

Protein Chemical Score ---> EAA value in the food compared to EAA in PAAP

EAA composition and Chemical Score

EAA Prot.Ref. Rice Fish Corn Soybean

Isoleusin 250 290 317 228 333

Leusin 440 654 474 535 484

Lysin 340 234 549 268 66% 395

Fenilalanin 200 353 231 351 309

Tyrosin 180 171 159 88% 217 201

Methionin 220 113 178 117 81% 86 60%

Threonin 240 268 283 268 247

Tryptophan 60 66 62 219 42% 86

Valin 310 399 327 324 328

First LAA tryptophan tryptophan methionin

Second LAA tyrosin lysin tryptphan

Third LAA - methionin -

How to increase protein quality?

- Increase protein quality in the food

- Increase the LAA concentration

---> SUPPLEMENTATION

Two fashions on supplementation

1. LAA Supplements- Add crystallized of pure AA

- Expensive , ineffective

E.g. : premix rice

2. Supplementation by one or more food which contain various LAA

E.g. :

Rice have first LAA, lysin, mix with peanuts which have first LAA, methionin

Protein metabolismProtein digested by proteolytic enzymes

starting in the stomach ---> in duodenum, ileum and jejunum ---> form amino acids

AA absorbed through the intestine by active transport mechanism and assisted by carrier protein

AA ---> portal vein ---> liver AA from the liver ---> blood ---> distributed

to the cell organs

Protein excretion ---> faeces ---> Undigested Dietary Protein and endogen protein

Healthy individual ---> protein does not excreted through urine, but the metabolite does Protein Metabolic Waste Product ---> Urinary Nitrogen : urea and non protein nitrogen (creatinin and uric acid)

Amino Acid Pool

There are some amino acids in the body that ready to use by any chance they needed as energy reserve ; e.g. : albumin and skeletal muscle cell.

Amino acids reserve mentioned above is called AMINO ACID POOL

Tissue amino acids and Amino Acids Pool are in an equilibrium and dynamic state.

Protein excretion higher than protein intake will perform negative nitrogen balance --> reduce body protein --> hypoalbuminemia or hypoproteinemia

Protein intake higher than protein excretion --> positive nitrogen balance.Excess protein intake will increase production of urea, creatinin and uric acid in the body

Protein RDA on various condition : Children : 1,2-2,2 gr/kg BW/day Adult : 0,8-1,0 gr/kg BW/day Pregnancy : adult + 12 gr/day Lactating first

6 month : adult + 16 gr/day Lactating second

6 month : adult + 12 gr/day Lactating

> a year : adult + 11 gr/day

Diseases related to protein metabolism disorder

1. PEM (Protein-Energy Malnutrition)

Protein deficiency always happen simultaneously along with energy deficiency.

Protein deficiency could occur in adequate energy intake --> KWASHIORKOR

2. HOMOCYSTEINURIAInborn error of metabolism disease. Occur in cystathionin synthetase enzyme deficiency. Methionin metabolite accumulated and huge amount of homocystein.Children usually died at adolescent.

3. PHENYLKETONURIAInherited, due to phenylalanin synthetase enzyme deficiency.

Citric acid

-Keto glutaric acidSuccinic acid

Oxaloacetic

Arginine

Histidine

Hydroxyproline

Proline

Glutamic acid

Valine

Aspartic acid

CystineCysteineMethionineGlycineSerineThreonine

Alanine

Acetyl CoA

FAT

CARBOHYDRATE

Pyruvic acid

IsoleucinLeucinLysinePhenylalanineTyrosine

Acetoacetate

KREB’S CYCLE